Among the various molding processes of plastic molds, injection molding is the most commonly used one. The theory indicates that injection molding has the advantages of strong material applicability, the ability to mold products with complex structures at one time, mature process conditions, high product precision, and low consumption costs. Therefore, injection molded products account for the proportion of plastic products from time to time. With the increase, related processes, equipment, molds and consumption management methods have also been rapidly developed.
Thermoplastics are plastic parts that can be molded into a certain shape when heated, and adhere to the finalized shape after cooling. If it is heated again, it can be softened and melted, and a plastic part with a certain shape can be made again, and it can be stopped repeatedly, which is reversible.
Because thermoplastics are materials that can be repeatedly heated and softened and cooled and hardened, they can be repeatedly solidified and formed by heating and melting, so the waste of thermoplastics can usually be recycled and reused, which is called the so-called “secondary material”. The post-shrinkage of injection molded parts refers to that when the injection molded parts are molded, a series of stresses are generated due to their internal physical, chemical, and mechanical changes. After the injection molded parts are molded and solidified, there are residual stresses. After the injection molded parts are demolded, due to various residual stresses , It will cause the size of injection molded parts to decrease again.
Usually, the injection molded part shrinks significantly within 10 hours after demolding, and it is basically shaped after 24 hours, but it takes a long time to reach the final shape. Generally speaking, the post-shrinkage of thermoplastics is greater than that of thermoset plastics, and the post-shrinkage of injection molded and injection molded parts is greater than that of shrink-molded injection molded parts.
Post time: Aug-17-2021